Aggregata octopiana (Protista: Apicomplexa): a dangerous pathogen during commercial Octopus vulgaris ongrowing     

Gestal  Camino; Guerra  Angel; Pascual  Santiago 《ICES Journal of Marine Science》2007,64(9):1743-1748

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In two waters: contemporary evolution of lagoonal and marine white seabream (Diplodus sargus) populations     

Mercedes González-Wangüemert  Ángel Pérez-Ruzafa 《Marine Ecology》2012,33(3):337-349

Brackish water ecosystems are often exposed to wide variations in environmental variables, including temperature and salinity, which may cause strong selective pressures on organisms modifying the genetic patterns of species. The aim of this work was to test whether there is a ‘divergence-with-gene flow’ in coastal lagoon populations of white seabream (Diplodus sargus) (Ria Formosa, S Portugal and Mar Menor, SE Spain) respect to four marine populations, by using partial sequences of cyt b mitochondrial gene and information from nine microsatellite loci. Genetic diversity was highest in both coastal lagoons (Mar Menor and Ria Formosa) considering mitochondrial and nuclear markers. Although some of F_ST population pairwise comparisons were not significant, analyses of molecular variance (AMOVAs) detected differences between groups (coastal lagoon and marine) close to significance. Also, only two haplotypes (Cytb-17 and Cytb-18) were detected in both coastal lagoon sampling sites and these localities (Mar Menor and Ria Formosa) showed the highest number of singletons, some of them with a high number of mutations, as has been already described for other Mar Menor populations (Pomatochistus marmoratus and Holothuria polii). Also, several tests detected significant positive and balancing selection considering mtDNA and microsatellite data. These data support the hypothesis of selection as one of the drivers of the genetic differences found between coastal lagoon and marine populations. The life strategy adopted by Diplodus sargus in coastal lagoons allows it to decrease its mortality rate and improve the heritability of its genes. Also, the increase time spent in coastal lagoons with different temperatures and salinities favours the fitness selection and the maintenance of exclusive haplotypes and genotypes in coastal lagoon inhabitants favouring the ‘divergence-with-gene-flow’.  相似文献   

West versus East Mediterranean Sea: origin and genetic differentiation of the sea cucumber Holothuria polii          下载免费PDF全文

Sara Valente  Ester A. Serrão  Mercedes González‐Wangüemert 《Marine Ecology》2015,36(3):485-495

We studied the genetic structure of the sea cucumber Holothuria (Roweothuria) polii (Delle Chiaje 1823) by analysing the mitochondrial DNA variation in two fragments of cytochrome oxidase I (COI) and 16S genes. Individuals were collected in seven locations along the Mediterranean Sea, which cover a wide range of the species distribution. We found high haplotype diversity for COI and moderate diversity for 16S, and low nucleotide diversity for both genes. Our results for the COI gene showed many recent and exclusive haplotypes with few mutational changes, suggesting recent or ongoing population expansion. The Western and Eastern Mediterranean populations exhibited slight but significant genetic differentiation (COI gene) with higher genetic diversity in the East. The most ancient haplotype was not present in the westernmost sampling location (SE Spain). The oldest expansion time was observed in Turkey, corresponding to mid‐Pleistocene. Turkey had also the highest genetic diversity (number of total and exclusive haplotypes, polymorphisms, haplotype and nucleotide diversity). This suggests that this region could be the origin of the subsequent colonizations through the Mediterranean Sea, a hypothesis that should be assessed with nuclear markers in future research.  相似文献   

Stellar populations in barred spirals     

Simon Cantin  Carmelle Robert  Anne Pellerin  Mercedes Moll 《New Astronomy Reviews》2006,49(10-12):536

OASIS observations obtained at the Canada–France–Hawaii Telescope for the spiral galaxies NGC 4900 and NGC 5430 produce one spectrum for each 0.41″ element of the 11″ × 15″ field of view. This allows for the spatial characterisation of the different stellar populations. From these observations we study the young (10 Myr) and older stellar populations using evolutionary synthesis codes. Based on the gas emission lines, we find that the young populations are located in relatively small regions and dominate the integrated flux. In NGC 4900, the young populations are distributed in a bar-like structure featuring a hole near the position of the galaxy’s centre. The young stellar populations of NGC 5430 form a nuclear ring and two patches at the base of the spiral arms. Based on Mg₂ and FeI absorption lines, we find that in both galaxies, the young stars are superimposed on a relatively homogenous population of a few Gyr.  相似文献   

Hydrogeological and mineralogical analysis of the pre‐Romanesque monument of Santa María del Naranco,Asturias, Spain     

Beatriz Gonzlez Fernndez  Celia Marcos Pascual  Eduardo Menndez Casares 《Geoarchaeology》2010,25(4):497-513

The church of Santa María del Naranco is an important monument from the pre‐Romanesque period of Asturian art. Here we present research that locates the probable source of travertine used in the construction of a vault within this monument. Since the genesis of this travertine is associated with spring activity, and archival evidence suggests that stone procurement during this period tended to be local, we surveyed existing carbonated aquifers within a 5‐km radius of the monument. We identified a spring (Sopeña) with an associated outcrop of discontinuous travertine that appeared to have been quarried in the past. We conducted X‐ray powder diffraction, electron microprobe, and inductively coupled plasma mass spectrometry analyses of samples extracted from the suspected travertine source, an additional more distant travertine quarry for comparison, and the vault. Matching mineralogy and geochemistry indicate that the Sopeña travertine was the probable source of rock material used in the construction of the vault. This study provides insight into local ancient monument construction and can assist in procuring original stone material for historical restoration. © 2010 Wiley Periodicals, Inc.  相似文献   

Intrinsic and specific vulnerability of groundwater in central Spain: the risk of nitrate pollution   总被引：5，自引：1，他引：4  

Juan J. Martínez-Bastida  Mercedes Arauzo  Maria Valladolid 《Hydrogeology Journal》2010,18(3):681-698

The intrinsic vulnerability of groundwater in the Comunidad de Madrid (central Spain) was evaluated using the DRASTIC and GOD indexes. Groundwater vulnerability to nitrate pollution was also assessed using the composite DRASTIC (CD) and nitrate vulnerability (NV) indexes. The utility of these methods was tested by analyzing the spatial distribution of nitrate concentrations in the different aquifers located in the study area: the Tertiary Detrital Aquifer, the Moor Limestone Aquifer, the Cretaceous Limestone Aquifer and the Quaternary Aquifer. Vulnerability maps based on these four indexes showed very similar results, identifying the Quaternary Aquifer and the lower sub-unit of the Moor Limestone Aquifer as deposits subjected to a high risk of nitrate pollution due to intensive agriculture. As far as the spatial distribution of groundwater nitrate concentrations is concerned, the NV index showed the greatest statistical significance (p?<?0.01). This new type of multiplicative model offers greater accuracy in estimations of specific vulnerability with respect to the real impact of each type of land use. The results of this study provide a basis on which to guide the designation of nitrate vulnerable zones in the Comunidad de Madrid, in line with European Union Directive 91/676/EEC.  相似文献   

The Canary Eddy Corridor: A major pathway for long-lived eddies in the subtropical North Atlantic     

Pablo Sangrà  Ananda Pascual  Ángel Rodríguez-Santana  Francisco Machín  Evan Mason  James C. McWilliams  Josep L. Pelegrí  Changming Dong  Anna Rubio  Javier Arístegui  Ángeles Marrero-Díaz  Alonso Hernández-Guerra  Antonio Martínez-Marrero  Maricel Auladell 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(12):2100-2114

We report, from remote sensing and in situ observations, a new type of permanent structure in the eastern subtropical Atlantic Ocean, that we call the “Canary Eddy Corridor”. The phenomenon, is a zonal long-lived (>3 months) mesoscale eddy corridor, whose source is the flow perturbation of the Canary Current and the Trade Winds at the Canary Islands. The latitudinal range of the corridor spans 22°N–29°N and extends from the Canaries to at least 32ºW, near the mid-Atlantic. This is the main region of long-lived westward-propagating eddies in the subtropical northeast Atlantic. From a age-distribution study we observe that at least 10% of mesoscale eddies in this region are long-lived, with a dominance of anticyclones over cyclones. Another four westward-propagating eddy corridors were also detected: two small corridors north and south of the Azores Front; a small zonal corridor located near 31ºN, south of the island of Madeira; and a small corridor located near the Cape Blanc giant filament. The existence of these corridors may change, at least for the northeastern subtropical Atlantic, the general idea that mesoscale eddies are disorganized, ubiquitous structures in the ocean. The Canary Eddy Corridor constitutes a direct zonal pathway that conveys water mass- and biogeochemical properties offshore from the Canary Island/Northwest Africa upwelling system, and may be seen as a recurrent offshore pump of organic matter and carbon to the oligotrophic ocean interior. Estimates of volume and mass transport indicate that Canary Eddy Corridor westward transport is more than one-fourth of the southward transport of the Canary Current. The westward transport of kinetic energy by the eddies of the Canary Corridor is as important as the southward transport by the Canary Current. The total primary production related to the Corridor may be as high as the total primary production of the northwest Africa upwelling system for the same latitude range.  相似文献   

New data (U–Pb, K–Ar) on the geochronology of the alkaline-carbonatitic association of Fuerteventura, Canary Islands, Spain     

Mercedes Muoz  Juana Sagredo  Cristina de Ignacio  Javier Fernndez-Surez  Teresa E. Jeffries 《Lithos》2005,85(1-4):140-153

Zircons from a nepheline-syenite of the Fuerteventura Basal Complex were dated by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). The age obtained from a total of 21 U–Th–Pb analyses is 25.4 ± 0.3 Ma (2σ) indicating a late Oligocene–early Miocene crystallization. This age is consistent with new K–Ar ages on nepheline-syenites and pyroxenites, and contradicts previously published ³⁹Ar–⁴⁰Ar (feldspar) ages that were interpreted to represent a late Cretaceous–early Paleocene, pyroxenitic–syenitic magmatic episode. These new geochronological data are consistent with both field observations and most of the previously published ages on alkaline silicate rocks and associated carbonatites of Fuerteventura. Therefore, they strongly support the existence of a single, late Oligocene–early Miocene event of alkaline–carbonatitic magmatism in the Basal Complex of Fuerteventura, taking place at approximately 25 Ma and comprising: alkaline-pyroxenites, melteigites-ijolites, nepheline-syenites and carbonatites, as well as their volcanic equivalents and associated dykes.

These new data provide an estimate for the length of time that it took the island to grow, thus eliminating one of the major problems in explaining its development by a hot-spot model.  相似文献   

Geological constraints on massive sulphide genesis in the Iberian Pyrite Belt     

R. Sáez  G.R. Almodóvar  E. Pascual 《Ore Geology Reviews》1996,11(6):429-451

The Iberian Pyrite Belt (IPB), SW Iberian Peninsula, Spain and Portugal, one of the most famous and oldest mining districts in the world, includes several major concentrations of massive sulphides, unique on Earth (e.g., Riotinto, Neves Corvo), as well as a large number of smaller deposits of this same type. All these deposits, in spite of their general similarities, show significant differences in geological setting, age, relations to country rocks, hydrothermal alteration, mineralogy and geochemistry. As a consequence of a review of the available data in the IPB, together with new findings on volcanism, hydrothermal alteration and ore mineralogy, we propose a modified genetic scenario, that can account particularly for the diversity of the geological situations in which sulphide deposits occur, as well as for their mineralogical and petrological diversity. It is concluded that there is no direct genetic relationship between felsic volcanic activity and massive sulphide deposition in the IPB, and that most of the massive sulphide bodies, including all of the giant ones, are closely related to hydrothermal vents, being therefore proximal. The available isotopic data yield additional genetic information: (a) Homogeneous lead isotope values indicate a single (or homogenized) metal source; (b) sea and connate water are the fluid reservoirs for hydrothermal input, and (c) bacterial reduction of sulphur is the most probable cause of differences in δ³⁴S between stockwork and massive sulphide mineralizations. Finally, current geodynamic models suggested for the IPB are discussed. It is suggested that an intracontinental, ensialic rift or pull-apart environment is the most probable genetic environment for the IPB mineralizations.  相似文献   

Determination of the principal reflectances of an absorbing uniaxial mineral,ilmenite, from measurements on random sections     

C. Marcos Pascual  J. M. Virgos Rovira 《Physics and Chemistry of Minerals》1988,16(1):51-54

We show the steps followed for obtaining the principal reflectances of an absorbing uniaxial mineral, ilmenite, by use of the inference method derived from statistical reflectance parameters of the sample. The values obtained in air, at 580 nm, with this method are: R =19.6±0.3 and R =17.8±0.3.  相似文献